In the drilling of wells with rotary tools using an aqueous drilling fluid, major difficulties are caused by the penetration of natural formations. Certain formations, such as gypsum, will "cut" the drilling fluid causing particles within the drilling fluid to flocculate and the viscosity to become too high. In such instances there is danger of the drill pipe twisting in half, of gas cutting the mud, or of a blowout occurring. Another difficulty which is frequently encountered in deeper wells is gelation and/or thickening of the drilling mud due to high temperatures encountered in deep wells. In such instances the drilling mud actually gels and/or thickens and greatly increases the pump pressures required for circulating the drilling mud.
The most successful solution to these problems has been the addition of drilling additives or thinners which consist of sulfoalkylated tannins or heat treated sulfoalkylated tannins with inorganic water soluble cationic and anionic compounds of inorganic chromium (VI) and optionally lignite. Unfortunately some of these chromium (VI) compounds are potentially carcinogenic. Thus, it would be a significant contribution to the art to discover a compound which may replace inorganic chromium (VI) compounds now in use that is not as potentially carcinogenic.